Chemical properties of Manganese

Manganese is more electropositive than its neighbours in the periodic table, but despite this manganese react with air at room temperature very slowly. Heated manganese powder can react with oxygen and nitrogen from the air with subsequent formation of manganese oxides with different oxidation state, mainly Mn₃O₄ and MnO₂ and manganese nitride Mn₃N₂. At room temperature very slowly reacts with water:

Mn + 2H₂O -> Mn(OH)₂ + H₂

Manganese easily reacts with common acids, like sulphuric acid or hydrochloric acid with formation of Mn²⁺ ions. Mn²⁺ ions in aqueous solution are presents as a aquated colourless complexes [Mn(OH₂)₆²⁺

Liquid Manganese can produce carbides (Mn₃C), electrically conductive silicides (Mn₃Si), different borides (for example Mn₄B), phosphides (for example Manganese monophosphide MnP).

Manganese oxidation states are +2, +3, +4, +6 and +7 (+1 and +5 very unusual) and therefore manganese can formate following oxides: MnO, Mn₂O₃, MnO₂, MnO₃ and Mn₂O₇. MnO₃ was newer separated. Mn₂O₇ is a very aggressive liquid, which is unstable at high temperatures and can explode.

Another very important manganese compounds is manganate - compounds that contains the tetrahedral manganate ion MnO₄^2-. MnO₄^2- ion is paramagnetic. Also magnesium (Mn⁷⁺) can form Permanganates, a strong oxidizing agents.

Basic chemical reactions for manganese:

3Mn + 2O₂ -(t)-> Mn₃O₄
3Mn + N₂ -(t)-> Mn₃N₂
Mn + 2H₂O -(t)-> Mn(OH)₂ + H₂
Mn + Cl₂ -> MnCl₂
Mn + Br₂ -> MnBr₂
Mn + I₂ -> MnI₂
Mn + F₂ -> MnF₂
2Mn + 3F₂ -> 2MnF₃
Mn + 2H₂SO₄(conc.) -> MnSO₄ + SO₂ + 2H₂O
3Mn + 8HNO₃ -> 3Mn(NO₃)₂ + 2NO + 4H₂O